System defence boats: an experiment

[barnest2]

I'm sat up tonight, away from my books, and I have come to a quandary...

Could you design a ship that used only solid munitions, missiles, rail-guns and the like?

I assume you could, but could it have effective point-defence under the current rules with such a restriction?

Also, say you are limited too... either Tl-10 or Tl-12, and again, no lasers or particle beams etc, how would you design such a craft.

I'll be having a crack at this myself once I'm back at my books, I just wondered what others would make of it?

 

[phavoc]

Could you? Yes. But their effectiveness would be limited by their magazine capacity (at least offensively).

Without a sandcaster, their defense is limited to passive means - ship agility, armor and electronic warfare.

Nothing says you cannot do it, but they would have limited survivalability and would be hampered without a source of munitions.

 

[barnest2]

Hmm... I was pondering the possibility of using a sandcaster (maybe with pebbles?) as point defence against missiles... I thought maybe that would work... Hmmm...

Maybe it could lead to a rise in actual EW vessels?
It's that or design an anti-missile system... Do you think maybe the Vulcan (from the CSC) could do it?... or are the ranges too much...

And I know about the magazine capacity, that would be kinda the point... or at least it would amuse me... and could lead to stuff like battle-riders, which while carrying less ships, have a huge cargo bay full of missiles...

 

[Rikki Tikki Traveller]

A turret mounted railgun should be an effect point defense weapon against missiles.

 

[locarno24]

Could you design a ship that used only solid munitions, missiles, rail-guns and the like?

Well...obviously yes, but that's not really what you're asking.

I assume you could, but could it have effective point-defence under the current rules with such a restriction?

Yes and no. Sandcasters are fine for point defence against long-ranged missile fire, as well as lasers.


For a missile boat, missile launchers, heavy missile/torpedo launchers and sandcasters are fine.

For a brawler, railgun bays and sandcasters (which are physical ammo in my book. Use pebbles rather than sand if it makes you feel better).

Both should be agile - the former wants to keep at long range where it has the advantage of reach and its sandcasters have the time to engage incoming missiles. The latter needs to get up close and personal as fast as possible and start laying about it with those Auto-12 railgun bays. So I'd go for as high a thrust score as you can manage.

What sort of displacement

Hmm... I was pondering the possibility of using a sandcaster (maybe with pebbles?) as point defence against missiles... I thought maybe that would work... Hmmm...

From High Guard:

Sandcasters are as effective as lasers as long as the missile it is defending against is fired from at least medium range.

Also look up the rules in the book for Chaff ammunition

 

[barnest2]

Thanks thats really helpful

In terms of displacement I was gonna be designing a fleet of the things, but for the experiment... shall we say, 4-600 ton, no jump, solid munitions only?

 

[locarno24]

Okaaay....

TL12 400 dTon SDB, designed to be seriously gun-happy. I make no claims that this ship is invincible, but it certainly packs a punch disporportionate to its displacement against medium-weight foes.

Hull:

Well, if it's an SDB, it's operating in a populated system and has no need to jump, its fuel requirements will be pretty low, and if it's dependent on resupply for hard rounds then it'll be meeting up with a tender or returning to base regularly. As a result, self-refuelling capacity isn't really needed.

TL12 Class 4 Dispersed Hull

Armour:

The way armour works in traveller, you might as well take your TL in the best armour available as a first choice. TL12 Crystaliron makes you functionally immune to nukes, pulse lasers and similar, takes the sting out of particle beams. Add radiation shielding and your bridge and computer are hardened into the bargain.

Drives:

A maxed-out M-Drive is almost a given for a brawler - speed to close, agility to dodge and so on. This requires a Class M drive to give you the capacity for 6-G manouvres, and hence requires a similar class power plant. A TL12 drive will be nice and compact, which is good - a ship like this is always going to have a use for saved tonnage, whether for armour, hull reinforcement, or ammunition.

Fuel:

There's really no reason for an SDB to carry more than 2 Weeks fuel. Based off the Transit Times table, with a 6G drive six days is a round trip to anywhere in the same system.

Bridge:

It's a warship, so Holgraphic Controls are usually a good buy. High initiative means lots of reactions, which pairs nicely with a high thrust drive to allow lots of dodges.

Electronics:

Very Advanced are the cutting edge of military hardware at TL12. So might as well be used.

Computer:

Again, take the best you can. Rating 20 lets you run some shiny software.

Software:
Evade/2 is cheap and helps as you close. Once within range, you need to be killing things quickly, so close it down and boot up Fire Control/4, which is enough to land accurate autofire on most targets.

Weapons:
The weakness of the railgun is that it's actually no more powerful than the turret mount particle beam - which is five times less massive and available a tech level earlier. In order to really get people's attention, bay weapons are the order of the day. Fortunately, that same high-powered fusion plant that lets you run a thrust-6 M-Drive also allows a 400 dTon ship to run two bay weapons. Taking advantage of the miniaturized TL12 railgun, you can fit two large bay mounts - two auto-12 bursts every turn, or the equivalent of 12 barbette mounts on a 400 dTon ship.

Point defence is easy. Sandcasters in turrets. I'm never quite sure how the point defence rules work with multi-barrel turrets, so I'm ducking the question and taking single turrets. TL9 Mounts can take the Accurate upgrade, which is good for the point defence role.



Ammunition:

Railguns are easy - a large railgun bay has 400 rounds of internal storage, the equivalent of a 20 dTon magazine on the ship. Significantly increasing the ship's ammo reserves over what it's carrying already is next to impossible, so let's not bother.

Sandcaster ammo is simple - one dTon per turret each of Chaff and Sand gives you a nice, flexible defence.



Crew:

Using the Full requirements, 16 crew should do it - 8 gunners, 2 engineers, three pilots, one navigator, and two officers. If you feel that the 'navigator' job is for jump-capable ships only, swap him for a medic.

That requires eight double staterooms all told.


Extras:

3 dTons of luxuries ups the living standard to that of Middle Passage (pretty good) and, since the ship will be operating in a populated system, escape pods might actually do some good. An armoury kits out the crew pretty well - with some (assumed) training and the armour and carbines drawn from the armoury, a marine contingent is pretty redundant. This ship isn't designed to board others anyway, just blow them to scrap.

As for other durability increases, a Reinforced Hull upgrade pushes the hull score by almost half again, allowing you to take significantly more punishment before those painful internal hits, and slapping armoured bulkheads on, around or under pretty much anything combat-essential means that systems take quite a beating before being disabled.





Pugilist-Class SDB

Hull: TL12 Class 4 Dispersed, Reinforced Hull (x1) - Hull 13, Structure 8
Armour: Radiation Shielded TL12 Crystaliron - Armour 12(+6)
M-Drive: TL12 Manouvre-M - Thrust 6
P-Plant: Fusion-M, Emergency Power - Rating 6
P-Plant Fuel: 2 Weeks
Bridge: Holographic Controls - Initiative +2
Electronics: Very Advanced - DM+2
Computer: Model 4 - Rating 20, Hardened (Radiation Shielding)
Software: Evade/2, Fire Control/4, Manouvre/0, Library
Hardpoint #1: TL12 Large Railgun Bay, 400 Rounds Ammunition Internal
Hardpoint #2: TL12 Large Railgun Bay, 400 Rounds Ammunition Internal
Hardpoint #3: Single Turret (TL9 Accurate Sandcaster)
Hardpoint #4: Single Turret (TL9 Accurate Sandcaster)
Ammunition: 40 Sand Barrels, 40 Chaff Barrels
Crew: 8 Double Staterooms
Extras: 3 dTons Luxuries, 16 Escape Pods, Armoury
Armoured Bulkheads: Armour, M-Drive, P-Plant, Fuel, Bridge, Weapons

Total Cost (ex Ammunition & Fuel): 374.5 MCr (337 MCr as a standard design)
Ammunition & Fuel (Full Load): 72,000 Cr
Monthly Maintenance: 31,215 Cr
Monthly Life Support: 24,000 Cr

 

[barnest2]

Jesus... I think I love it
Thats a lot of railgun, lets just hope it doesn't meet anything with long range guns

I'm assuming it doesn't have any cargo space left?
And those railgun bays are nasty...

 

[locarno24]

Technically it has 0.055 dTons of unused space, but when designing a ship I don't think it's worth mentioning something like that as it's that's not a cargo bay - it's a small cupboard.

And those railgun bays are nasty...

Not as much as you might think. Armour 12 will deflect most 3d6 hits, such that the 'average' railgun slug will only do about half a point of damage. This thing is better at picking on lighter armoured foes - if you want to take on a high TL capital ship without energy weapons, you need nuclear torpedoes.

 

[Mongoose Pete]

And those railgun bays are nasty...

Not as much as you might think. Armour 12 will deflect most 3d6 hits, such that the 'average' railgun slug will only do about half a point of damage. This thing is better at picking on lighter armoured foes - if you want to take on a high TL capital ship without energy weapons, you need nuclear torpedoes.

I designed a 800t heavy Darrian SDB around twin meson bays and twin railgun bays (extended range and very high yield) precisely because of this awesome weapon. Its a Swiss cheese maker!

 

[dalamar981]

Fortunately, that same high-powered fusion plant that lets you run a thrust-6 M-Drive also allows a 400 dTon ship to run two bay weapons. Taking advantage of the miniaturized TL12 railgun, you can fit two large bay mounts - two auto-12 bursts every turn, or the equivalent of 12 barbette mounts on a 400 dTon ship.

I thought that on non capitol ships that it was dispersement (400) divided by 1000 (.4) rounded down (0) multiplied by 6 (0) but with a minimum of 1 bay.

This is at least how the Apoc's spreadsheet calculates it. Is his formula wrong?

 

[DFW]

I designed a 800t heavy Darrian SDB around twin meson bays and twin railgun bays (extended range and very high yield) precisely because of this awesome weapon. Its a Swiss cheese maker!

I never understood using a railgun on a ship. You wouldn't able to hit anything that has a variable flight path at further than adjacent range.

 

[AndrewW]

Fortunately, that same high-powered fusion plant that lets you run a thrust-6 M-Drive also allows a 400 dTon ship to run two bay weapons. Taking advantage of the miniaturized TL12 railgun, you can fit two large bay mounts - two auto-12 bursts every turn, or the equivalent of 12 barbette mounts on a 400 dTon ship.

I thought that on non capitol ships that it was dispersement (400) divided by 1000 (.4) rounded down (0) multiplied by 6 (0) but with a minimum of 1 bay.

This is at least how the Apoc's spreadsheet calculates it. Is his formula wrong?

Close:

400 / 1,000 = .4
.4*6 = 2.4
Rounded down = 2 bays allowed.

 

[rinku]

I designed a 800t heavy Darrian SDB around twin meson bays and twin railgun bays (extended range and very high yield) precisely because of this awesome weapon. Its a Swiss cheese maker!

I never understood using a railgun on a ship. You wouldn't able to hit anything that has a variable flight path at further than adjacent range.

I agree, but they'd be more efficient than lasers against sitting ducks (ground targets, installations, ships with no maneuver), since range would not be an issue (note that normal space combat doesn't address this, you'd need special rules). Cheaper per munition than missiles for the task, too. I think High Guard pretty much has them in there as bombardment weapons which have a limited direct fire capacity at point blank range.

 

[DFW]

I agree, but they'd be more efficient than lasers against sitting ducks (ground targets, installations, ships with no maneuver), since range would not be an issue (note that normal space combat doesn't address this, you'd need special rules). Cheaper per munition than missiles for the task, too. I think High Guard pretty much has them in there as bombardment weapons which have a limited direct fire capacity at point blank range.

I agree. However to list them as ship to ship weapons (where your enemy can maneuver), is hilarious.

 

[BP]

Space combat game mechanics as a whole can be quite laughable - one has to suspend quite a bit of disbelief/twist reality to justify most of it...

One 'presumes' railgun bursts would have sufficiently high velocities and use lots of projectiles - helps that most Traveller ships are only capable of < 7G maneuvers.

Range should be limited by the spread of the rounds, though friendly fire can be a real possibility with this type of space weapon.

 

[DFW]

Space combat game mechanics as a whole can be quite laughable - one has to suspend quite a bit of disbelief/twist reality to justify most of it...
.

Not even close to what is required to have rail guns.

 

[locarno24]

Depends on the range to target.

At adjacent to close range - i.e. less than 10Km - I don't see that that's that unreasonable. Even a contemporary technology railgun (see the ONR research) has a reasonable expectation of achieveing a 2.5 Km/s muzzle velocity, which gives you a time of flight of 4s or less (maybe a few hundred metres displacement with a single continuous acceleration), and you're aiming at a 'real-time' target with light-speed sensors.

Difficult, but not impossible. With the railgun as described in Traveller having a higher muzzle velocity and being an auto-firing weapon, especially if one imagines the railgun round to have a shotgun effect (as is often described for missile warheads) and a significantly higher velocity (this is a weapon first available at TL9, so one would assume it's a gravetic railgun rather than a magnetic one).

Short range, on the other hand, runs up to 1250km, and I'll happily admit that aiming something at a moving target that's not either guided or has a relativistic speed at that distance is a tad optimistic at best.

 

[DFW]

Ya, I could auto fire out to 10km having a chance for some thing going ~50km/sec. The longer ranges (>150 km) being pretty much impossible.

 

[locarno24]

Again, depends on the velocity. I'd think that number looks about right, though.

If we assume that you can stand a chance of hitting if the ship's displacement since firing is more or less the same as it's dimensions, then a 3g, 100m across capital ship is still a potential target after 2.5-3s of flight - meaning a distance equal to three times the projectile's velocity (i.e. 150Km for a 50Km/s round)

The amount the target can displace is a direct function of the flight time. Assuming a 6G ship (worst case for non-small craft), then it's as follows

0.1s flight time: 0.29m - useless

0.5s flight time: 7.35m - useless for any reasonable sized ship

1.0s flight time: 29.4m - probably enough for small ships to dodge single shots, still probably useless given autofire

1.5s flight time: 66.2m - now relying on autofire to hit anything but really big ships

2.0s flight time: 117.72m - you're only really going to be able to hit ships whose size is in this order of magnitude or more.

3.0s flight time: 264.87m - next to impossible to hit a non-capital ship

4.0s flight time: 470.88m - even capital ships will be hard to hit. Of course few capital ships mount 6G drives...




A 2.5-3s flight time assumption, by the way, plays out fairly well in the real world - the longest confirmed sniper kill (a Houshold Guard Corporal ) hit at 2,475m with a weapon whose muzzle velocity of around 900m/s gives the shot about a two-and-a-half second flight time.